Alkaline Phosphodiesterase Activity of Goat Brain Cortex Ribosomes

Abstract

Abstract— The ribosome preparation of goat cerebral cortex was found to possess acid and alkaline phosphodiesterase (PDase) activities, the alkaline PDase activity was greater. The alkaline PDase activity increased sharply between pH 8 and 9 and showed maximum activity between 35° and 40°. The alkaline PDase lost about half of its activity on heating the ribosome preparation at 83° for 5 min. Storage at low temperature or freezing and thawing did not cause significant loss of enzymic activity, but prolonged dialysis beyond 24 hr in the cold against magnesium‐cacodylate buffer caused some loss of activity. Copper, cobalt, inorganic phosphate ions, EDTA, urea and detergents were found to be inhibitors of the PDase activity. Differential inactivation in the presence of arsenate and zinc ions suggests the distinctness of the PDase activity from the phosphomonoesterase (PMase) activity of the ribosome preparation. The enzyme appeared firmly bound to ribosomal particles and attempts to solubilize it were unsuccessful.

Mescaline-induced changes of brain-cortex ribosomes. Effect of mescaline on the stability of brain-cortex ribosomes

“…Phosphodiesterase activity was measured by the method of Frisch-Niggemeyer & Reddi (1957) with bis-p-nitrophenyl phosphate as the substrate. The procedure, which was basically the same as that for phosphomonoesterase, has been described in detail by Datta & Ghosh (1963c) and Datta, Ghosh & Bhattacharyya (1969). The specific activity of the phosphodiesterase is expressed as nmol ofp-nitrophenol liberated/mg ofribosomal protein per h. Occasionally, the activity was checked by using adenosine 2': 3'-cyclic phosphate as a substrate as described by Drumond, Iyer & Keith (1962).…”